1. Field of the Invention
The present invention relates generally to a lead frame, and more specifically to a lead frame for use in the quad flat no-lead package.
2. Description of the Related Art
In the quad flat no-lead (QFN) package, a chip is bound to each of units of a lead frame, and then an epoxy resin is poured into each of the units to mold the chip. Thereafter, an operator will attach a UV tape to the back of the lead frame, and then place the lead frame on a ceramic plate for cutting the units.
FIG. 1 shows a square unit 10 of a lead frame according to a prior art, having four right-angled comers 12. Because the contact areas between four sides 14 of the unit 10 located at the corner of the lead frame and the UV tape are insufficient, the sides 14 of the unit 10 may easily fly off under the action of a cutting blade rotating in high speed and a high-pressure water column during cutting process of the unit 10, probably causing the cutting blade and the chip to be damaged by the flying sides 14.
In order to eliminate the above-mentioned drawback, some operators will attach another UV tape to the sides 14 of the unit 10 located at the corner of the lead frame, but the operation time, manpower and material costs will be increased due to the extra UV tape.